Onset Of Photophase Research Articles

Emergence and Reproductive Rhythm of Clostera anastomosis (Lepidoptera: Notodontidae)

Abstract Clostera anastomosis L. (Lepidoptera: Notodontidae) is a serious defoliator of poplar, Populus spp., trees in China. To establish a baseline of information for possible ecological management of this pest, we studied its emergence, courtship, mating, and oviposition behaviors in the laboratory at 27 ± 1°C and 60 ± 10% relative humidity under a 14:10-h (light:dark) photoperiod. Under these conditions, peak emergence of female adults occurred in the sixth day after pupation, and peak emergence of males was in the seventh day after pupation. Emergence for both sexes occurred throughout the day. Courtship behavior began at the sixth hour of scotophase, reaching peak activity between the 10th hour of scotophase and the first hour of photophase. The courtship and mating success rate were highest for 1-d-old females, and then gradually decreased with age until no mating was observed after females were 4 d old. With 1-d-old females, mating was only observed from the seventh hour of scotophase to the first hour of photophase, with peak activity at 0.5 h after the onset of photophase. Oviposition primarily occurred within 3 d after mating, with 49.8% of the eggs being deposited during the first day after mating. These results demonstrate that there are distinct circadian rhythms in adult emergence and subsequent reproductive behavior of C. anastomosis, thus providing a basis for development of monitoring and management strategies of this pest.

Mating Behavior of Mahanarva spectabilis (Hemiptera: Cercopidae) Under Laboratory Conditions

The mating behavior of Mahanarva spectabilis (Distant) was studied under laboratory conditions. Virgin adults were individually maintained in transparent cages for observation of the mating sequence. Mating behavior of 23 couples was monitored during the photophase portion of the day. Copulation was observed in 17 of the 23 pairs. The mating sequence includes male approaching the female, mounting of the female, and copulation. Of the 17 mating pairs, 70.6 % mated on the second day after emergence. Most of the copulations began between 8 and 9 h after the onset of photophase. The average duration of copulation was 268 ± 24.9 min, and most pairs mated once or twice during their lifetimes. The mating behavior of M. spectabilis is important to understand because it determines the age and ideal time for further behavioral testing, which is essential for determining the cues involved in the communication system of the species.

Male-Produced Sex Pheromone of the Cerambycid Beetle Hedypathes betulinus: Chemical Identification and Biological Activity

We identified, synthesized, determined the diel periodicity of release, and tested the bioactivity of components of the male-produced sex pheromone of Hedypathes betulinus (Coleoptera: Cerambycidae: Lamiinae). Gas chromatographic-mass spectrometric analysis of headspace volatiles from adult beetles showed three male-specific compounds, which were identified as (E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (major component), (E)-6,10-dimethyl-5,9-undecadien-2-one (geranylacetone), and (E)-6,10-dimethyl-5,9-undecadien-2-ol. Release of these chemicals was dependent on time of the photoperiod and presence of the host plant. Pheromone release took place primarily during the photophase, with maximum release occurring between 4 and 6hr after the onset of photophase. The amount of pheromone released by males was much greater when they were in the presence of their host plant than when they were not. In Y-tube olfactometer tests, a ternary mixture of the compounds was attractive to female beetles, although the individual compounds were not attractive by themselves. Addition of volatiles from the host plant greatly increased the attractiveness of the ternary pheromone mixture and of the major pheromone component alone.

Towards the identification and synthesis of the sex pheromone of the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

The objective of this work was to characterize the sexual behavior of the citrus leafminer, Phyllocnistis citrella Stainton, as the foundation for the isolation, identification, and synthesis of the complete sex pheromone of this species. Mating occurred in a time window of 2h, starting 1h before the onset of photophase. The large majority of tested insects mated in the first two days after emergence, with no significant difference between mating at day 1 and day 2. A stereotypical courtship and copulation behavior were described for this species. When mating was successful, the copulation was recorded in average for 49.6 min. In Y-olfactometer tests conducted at the time of mating activity, males were strongly attracted to caged virgin females as well as to extracts from putative pheromone glands.

Role of juvenile hormone-esterase in mating-stimulated egg development in the moth Heliothis virescens

Juvenile hormone (JH) titer in virgin females of Heliothis virescens is significantly lower than that in mated females of the same age. The JH titer in virgin females follows a diel pattern in which it begins to increase towards the end of photophase, remains high around the onset of scotophase, and declines during scotophase. The titer reaches its lowest levels at the onset of photophase, and remains low during the first half of photophase. In mated females, the diel pattern of JH titers is not as pronounced. JH-esterase (JHE) activity in mated females is significantly lower than that of virgin females during photophase; JHE levels in the former are similar to levels seen in newly emerged females. JHE activity in mated females also exhibits a diel pattern, in which activity is low during photophase and high at the onset of scotophase. Evidence for the indirect involvement of JHE in the mating-stimulated egg development is provided by the effect of selected JHE inhibitors in inhibiting JHE activity and stimulating egg production in virgin females.

Rhythmicity of mating and oviposition inCallosobruchus subinnotatus (Pic) (Coleoptera: Bruchidae)

Mating and oviposition behaviors were studied inCallosobruchus subinnotatus. Copulation was most frequent during the late scotophase, 2–3 h before onset of photophase. The females were less willing to mate during photophase, which increased the time to initiate mating while decreasing the duration of mating. Females exhibited increased movement prior to mating, resting immediately after mating, and remained stationary for 6 h when oviposition commenced. Multiple mating by both males and females affected the number of eggs laid, duration of mating, and uncoupling time at the end of mating. Females that mated two or three times laid more eggs than females that mated once or more than three times. Females that remainedin copula for less than 18 min showed greater readiness to remate than those that remainedin copula longer. There was a gradual decrease in the number of eggs females could lay with an increase in the number of previous matings by males.

Oviposition, Fecundity, and Body Size of a Pestiferous Midge, Chironomus crassicaudatus (Diptera: Chironomidae)

Field-caught gravid female Chironomus crassicaudatus Malloch in central Florida laid egg masses mostly in the morning at onset of photophase in the laboratory. Fifty-seven percent of these females laid a second egg mass in their adult life. Number of eggs averaged 1,338 and 245 per mass in the first and second mass, respectively. Average egg incubation period was 2 d, with initiation and cessation of egg hatch occurring at 1.5 and 5 d after oviposition, respectively. Relationship of body size and fecundity of female C. crassicaudatus was studied by measuring wing length and examining number of eggs per mass and parity. Body size of nulliparous and of parous females had a significant linear relationship with dry body weight. Larger females had a significantly higher number of eggs per mass and percentage parity than small females.

Melatonin replacement nullifies the effect of light-induced functional pinealectomy on nociceptive rhythm in the rat

Rats maintained on a 12 h daily photoperiod (12:12 LD cycle), exhibited a diunal variation in sensitivity to both heat-elicited and pressure-elicited pain, with low sensitivity at 2 h before the end of the scotophase and higher at 4 h after the onset of photophase. Functional pinealectomy induced by a single LL day effaced the baseline diurnal rhythm of sensitivity to pressure-elicited pain, and reversed that to heat-elicited pain. Oral administration of physiological doses of melatonin into functionally pinealectomized rats, nullified the effect of functional pinealectomy, restoring the normal baseline rhythms of both pressure-elicited and heat-elicited nociceptive responses. The role of melatonin in modulating nociception is discussed in light of an indoleaminergic-opioid system.

Production and Release of Sex Pheromone by Diaphania nitidalis (Lepidoptera: Pyralidae): Periodicity, Age, and Density Effects

The periodicity and effect of age of female Diaphania nitidalis (Stoll) on sex pheromone production and emission were determined by measuring the major pheromonal component, ( E )-11-hexadecenal, using gas chromatography. Volatile collections revealed that female D. nitidalis emitted at least 9.20 ng/h ( E )-11-hexadecenal during scotophase. Pheromone release typically increased sharply during the early hours of scotophase (1–5), peaked during the 5–7 h period, and decreased toward the onset of photophase. Similarly, the amount of pheromone present in extracts of pheromone glands increased at the onset and decreased toward the end of scotophase. However, the pheromone titer remained fairly constant from the third to ninth hours of scotophase. Female density within volatile collection chambers had a pronounced impact on the amount of pheromone emitted. As female density increased, pheromone emission decreased. Pheromone production was stable for 1- to 5-d-old females, but dropped sharply in 7-d-old females. In addition, the 7-d-old females began to oviposit unfertilized eggs within the collection chambers.

Adult German Cockroach (Orthoptera: Blattellidae) Feeding and Drinking Behavior as a Function of Density and Harborage-to-resource Distance

There was an effect of harborage-to-resource distance but no main effect of density on the frequency of feeding and drinking activity of adult Blattella germanica , videotaped continuously for 96 h. Feeding and drinking diel periodicity was more pronounced when the resource was placed further from the harborage with activity peaking ca. 2 h into scotophase and declining at the onset of photophase. Nongravid females and males fed and drank more often than gravid females, with a high percentage of females carrying oothecae never feeding or drinking during the recording period.

Rate and diel periodicity of pheromone emission from female gypsy moths, ( Lymantria dispar) determined with a glass-adsorption collection system

The rate of pheromone emission from wild and laboratory-reared gypsy moth ( Lymantria dispar) (Lepidoptera: Lymantriidae) virgin females was determined with an all-glass aeration apparatus. This device incorporated a bed of 1-mm glass beads to extract entrained pheromone from the air flowing over the protruded gland. The temporal pattern of emission was established by monitoring individual females after eclosion for 24 consecutive 2-hr intervals. At a constant 24°C, both wild and laboratory females exhibited a similar diel periodicity of pheromone emission. The mean release rate increased after onset of photophase, generally attained maximal levels between 1600 and 2200 hr and declined during scotophase. Pheromone was released continuously and the mean daily emission increased with age for both wild and laboratory moths. The mean emission rate over the 48-hr monitoring interval was 15.4 ng 2 hr for wild females vs 14.7 ng 2 hr for laboratory moths. The peak emission from 2-day-old laboratory moths was ca. 28 ng 2 hr compared with the ca. 25 ng 2 hr released by their wild counterparts. The calling periodicity of laboratory females was determined at a constant 24°C and under a natural temperature rhythm. At 24°C, the proportion of females calling exceeded 45% throughout the diel period, whereas under the temperature rhythm, calling was virtually eliminated by temperatures below 15°C, indicating that temperature acts as an exogenous cue to modify the expression of the calling rhythm and thus potentially the periodicity of pheromone emission.

Effect of day length and reproductive state on diel rhythms of luteinizing hormone levels in the plasma of white‐crowned sparrows, Zonotrichia leucophrys gambelii

AbstractPlasma levels of LH were measured through the course of 24 hours in photosensitive and photorefractory, adult male white‐crowned sparrows, Zonotrichia leucophrys gambelii, exposed to both long (20L, 4D) and short (8L, 16D) days. In photorefractory birds held on both long and short days there is an increase in plasma levels of LH late in the subjective day or soon after the onset of the scotophase. These levels remain high for most of the night and decline to low levels just after the onset of the photophase. In addition there is a second increase in circulating LH, 3–5 hours after the onset of the photophase, with a second minimum about 10 hours later.A similar rhythm occurs in photosensitive birds held on short days. Plasma levels of LH increase late in the day and remain high throughout most of the night. Lowest levels were measured just after onset of photophase. In contrast, circulating LH in photosensitive birds exposed to long days showed no discernable diel rhythm. During the night, plasma levels of LH of photorefractory birds, and also photosensitive birds on short days, are as high as those of photosensitive birds on long days.

Daily changes of neurosecretory type-II cell structure of Pieris larvae entrained by short and long days

The neurosecretory type-II cell (NS-II cell) group of each brain hemisphere consists of three kinds of cells: two small cells, six large ones, and two others having characteristic vacuolated endoplasmic reticulum (ER). Ultrastructural changes of large NS-II cells were observed through the fifth instar and diurnally when short-day and long-day larvae were compared. There were little differences between short-day and long-day larvae in cell structures on corresponding developmental days except for daily changes, but remarkable changes were observed every day through the instar. A secretory cycle through the instar was supposed being based on the ultrastructural changes in NS-II cells: reduced secretory activity on the first day, formation of organelles necessary for the synthesis of secretory materials throughout the instar on the second day, active synthesis and secretion of secretory material during the middle stage (third-fourth day), and reversion to a reduced level of cell activity after the cessation of feeding. In short-day larvae on the third to fourth day, NS-II cells contained large aggregates of secretory granules during the day except for the time of 13 hr after the onset of photophase when a decrease of secretory granules occurred. In long-day larvae, only a small amount of secretory granules was observed at 8 and 13 hr after the onset. Rough ER changed daily paralleling with the quantitative change of the secretory granules. Based on these differences of daily changes in NS-II cell activity between short-day and long-day larvae, it was concluded that photoperiodic time measurement of diapause induction depends on the daily secretory cycle entrained by the photoperiods during the larval stage.

Photoperiodic Induction of Diapause in Pieris rapae crucivora BOISDUVAL (Lepidoptera : Pieridae)

The incidence of pupal diapause in the cabbage white butterfly, Pieris rapae crucivora, fed on artificial diet was investigated under various photoperiodic conditions. The Tokyo population showed a typical long-day response curve with 50% incidence daylength of 12 hr 10 min at 20°C, while a high temperature of 25°C prevented the diapause incidence even under short photoperiods. When the 5th instar larvae which had been exposed to the short photoperiod were transferred to the long photoperiod, their diapause was prevented. In this case, the adult development was delayed in proportion to the intercal between the 4th molt and the transference to long photoperiod. One hour light-break at different times in the scotophase of short-day cycle reduced the diapause incidence. Especially, when the light-break was timed from 13 hr to 14 hr after the onset of photophase, diapause was almost prevented. Another slight reduction of diapause incidence occurred at 11-13 hr after the onset of scotophase. Larvae responded to supplementary illumination of even 1 lux for diapause inhibition. The present results correlated well with the photoperiodic conditions of the diapause incidence observed in the field late in October.